Procedures

The age, weight, and body mass index (BMI) in participants were recorded in detail, together with their history of gravidity, miscarriage, and implantation failure. A total of 70 eligible subjects were randomly assigned in a 2:1 ratio to the experimental group and the control group. Simple randomization strategy was performed for grouping. Random numbers generated using SPSS software (version 22.0) were sorted in ascending order, then those with numbers from 1 to 48 were assigned to the experiment group, while those with numbers from 49 to 70 were assigned to the control group. Upon the basis of the conventional therapy with multivitamins (take one pill daily with a meal), subjects in the experiment group (n = 48) received 8 weeks oral administration with Holofood three times daily at a dose of 10 g each time (taken 30 min before each meal), whereas subjects without Holofood consumption (n = 22) were set as control. Of the 70 participants, finally the data of 41 subjects in the experiment group and 20 subjects in the control group were included into the outcomes analysis. The CONSORT flow diagram of the participants in this trial was illustrated in Fig. 1.

CONSORT flow diagram of the participants in this trial

Holofood, a blend consisting of four kinds of prebiotics (galacto-oligosaccharides (GOS), inulin, yeast β-glucan, polydextrose) and four different plant-derived soluble dietary fibers (microcrystalline cellulose, erythritol, guar gum, steviol glycosides), was provided by Beijing Ruiqianjing Technology Development Co., Ltd., with the production license number of SC10611151014507.